The present invention relates to a magnetic tape cartridge in which a single reel with magnetic tape wound thereon is rotatably housed within a cartridge case, and more particularly to the structure of a write protection member for inhibiting magnetic recording onto the magnetic tape.
In existing magnetic tape cartridges, which are being used as storage media that are employed in external storage units for computers, etc., there is known a type where a single reel with magnetic tape wound thereon is rotatably housed within a cartridge case. This magnetic tape is employed to archive data for computers, etc. Since important information has been stored, a write protection member, movable between a write-enable position and a write-inhibit position, is installed so that problems, such as tape jamming, etc., do not occur and that magnetic recording is not performed on the magnetic tape inadvertently.
For example, as the aforementioned write protection member, a flat slide member is assembled to a side surface (rear surface) of the cartridge case. When the write protection member is moved to the write-inhibit position, the position of a recess in the write protection member is detected by contact of a sensor member provided in a drive unit, and data is inhibited from being written to the magnetic tape.
When it is installed in the cartridge case, the write protection member is provided on the rear surface (with respect to the insertion direction of the cartridge case into the drive unit) of the cartridge case, and the position of the write protection member (i.e., whether it has been positioned at the write-enable position or at the write-inhibit position) is detected at the rear surface of the cartridge case. In that case, however, it is necessary to move the sensor member when the cartridge case is loaded into or unloaded from the drive unit. Because of this, the sensor mechanism of the drive unit becomes structurally complicated and the aforementioned write protection structure is disadvantageous in assuring operational reliability.
From the points mentioned above, if a moved position of the write protection member can be detected through the bottom surface of the cartridge case, it is preferable in that the sensor mechanism of the drive unit can be simplified. However, it is desirable from the viewpoint of operability and display that a control portion for moving the write protection member be operated at a side surface (e.g., the rear surface) of the cartridge case.
However, in order to operate the write protection member at the side surface of the cartridge case and detect the position at the bottom surface, the following are required: the write protection member cannot be formed into a flat shape; it is necessary to assure the stable sliding function from the relationship with an installation space; it is necessary to reliably stop and lock the write protection member at the write-enable position and the write-inhibit position; the write protection member needs to be smoothly unlocked and moved; and it is necessary to assure satisfactory assembly performance of the write protection member with respect to the cartridge case.
Particularly, in the case where the write protection member is moved, the control portion of the write protection member is subjected to pushing-in force and therefore the locking force of the write protection member at the stopped position becomes so great that unlocking of the write protection member becomes difficult. Because of this, there is a possibility of operability being reduced.
In addition, the cartridge case is relatively large in height and accordingly the height of the write protection member is also increased. Because of this, some consideration is necessary to slide the write protection member in the lateral direction while preventing tilting of the write protection member.
The present invention has been made in view of the points mentioned above. Accordingly, it is the primary object of the present invention to provide a magnetic tape cartridge which is capable of assuring stable operation performance and assembly performance of the write protection member.
To achieve the object of the present invention mentioned above, there is provided a magnetic tape cartridge comprising a single reel with magnetic tape wound thereon; a cartridge case, which comprises an upper case and a lower case, for rotatably housing the single reel; and a write protection member for inhibiting magnetic recording onto the magnetic tape. The write protection member is slidably disposed within the cartridge case and comprises (1) a sliding main body; (2) a control portion provided on an outside surface of the sliding main body so that it is movable between a first position of enabling the magnetic recording and a second position of inhibiting the magnetic recording, while facing a control window formed in a side surface of the cartridge case; and (3) a protrusion, provided on a bottom portion of the sliding main body, which is inserted into a bottom hole formed in a sliding direction of the sliding main body in a bottom wall of the lower case and movable within the bottom hole. In the magnetic tape cartridge, a stopper piece is provided on an inside surface of the sliding main body so that it protrudes in a direction perpendicular to the sliding direction. Also, an elastically deformable guide wall is formed along the sliding direction in the cartridge case and has a first stopper groove and a second stopper groove at positions corresponding to the first and second positions. Furthermore, the stopper piece is fitted in the first or second stopper groove and holds a stopped position thereof.
In a preferred form of the present invention, the bottom hole of the cartridge case is formed adjacent to a side wall of the lower case. Also, a bottom wall, opposite to the side wall of the lower case and along the bottom hole, of the lower case has a sliding surface. Furthermore, the bottom portion of the sliding main body has a sliding surface which slidably contacts with the sliding surface of the lower case.
In another preferred form of the present invention, the cartridge case is provided with a regulation rib extending along the sliding direction of the sliding main body. Also, the inside surface of the sliding main body is brought into contact with the regulation rib when the control portion of the sliding main body is pushed inside the cartridge case.
In still another preferred form of the present invention, the stopper piece of the write protection member is slidable along an upper portion of the guide wall whose elastic deformation is great.
According to the present invention, the control portion of the write protection member is provided on the outside surface of the sliding main body so that it is movable between the first position of enabling the magnetic recording and the second position of inhibiting the magnetic recording, while facing the control window formed in a side surface of the cartridge case. This arrangement makes it possible to operate the write protection member at the side surface of the cartridge case. Also, a protrusion is provided on the bottom portion of the sliding main body of the write protection member and is inserted into the bottom hole formed in the bottom wall of the lower case and is movable within the bottom hole. This arrangement renders it possible to detect the position of the write protection member at the bottom surface of the lower case. On the other hand, the stopper piece of the write protection member is provided on the inside surface of the sliding main body so that it protrudes in a direction perpendicular to the sliding direction. Also, an elastically deformable guide wall is formed along the sliding direction in the cartridge case and has a first stopper groove and a second stopper groove at positions corresponding to the first and second positions. The stopper piece is fitted in the first or second stopper groove and holds a stopped position thereof. With this arrangement, the stopped position of the write protection member being at the first or second position can be locked and held. Also, even if the control portion of the write protection member is pushed inside the cartridge case, when the control portion is operated to move the write protection member from the first position to the second position, or from the second position to the first position, the guide wall is elastically deformed. Therefore, stable disengagement between the stopper piece and the stopper groove can be performed without requiring great force. Thus, satisfactory operability is obtained, whereby reliability can be assured.
In the case where the bottom hole of the cartridge case is formed adjacent to the side wall of the lower case, the write protection member becomes unstable, because an area in the bottom portion for supporting the write protection member is reduced. However, if the bottom wall, opposite to the side wall of the lower case and along the bottom hole, of the lower case has a sliding surface, and the bottom portion of the sliding main body has a sliding surface which slidably contacts with the sliding surface of the lower case, an area in the bottom portion for supporting the write protection member is increased and therefore the sliding of the write protection member can be stabilized.
In addition, if the cartridge case is provided with a regulation rib extending along the sliding direction of the sliding main body, the inside surface of the sliding main body is brought into contact with the regulation rib, when the control portion of the sliding main body is pushed inside the cartridge case to slide the write protection member. In this manner, the movement of the write protection member is regulated by the regulation rib and the pushing force of the stopper piece against the stopper groove is prevented from being excessive. Thus, stable disengagement of the stopper piece from the stopper groove is obtained.
Furthermore, if the stopper piece of the write protection member is provided so that it is slidable along an upper portion of the guide wall whose elastic deformation is great, more stable operation of the write protection member can be assured by effectively utilizing the elastic deformation of the guide wall.